Both federal postal services and private couriers face the challenge of sorting, handling and delivering mail pieces that are larger than letter size, such as parcels and flats. Tilt tray sorters and cross belt sorters are often the primary means for automated sorting of such mail pieces, but the output of such sorters often requires manual handling. Little has been done to facilitate such manual handling.
A typical tilt-tray or cross-belt sorter uses a series of carts mounting tilt tray or cross belt mechanisms. See for example Kofoed U.S. Pat. No. 5,690,209. The carts move around a generally oval shaped track or rail system that includes at least one induction area at which new items can be placed on a cart for sorting and a series of unloading zones at which the cart is activated to unload the item to a collection site usually outside of the track on which the carts move. The track is not a true oval but most often a rectangular shape with curved ends.
In connection with a commercial tray sorter known as the RSU tray sorter, the term “virtual sorter” was used to describe a tilt tray sorter with two or more induction points spaced along the perimeter of the oval track with multiple divert points (unloading areas) between induction points. The portion of the sorter that includes one induction point, its associated scanner, and the divert points between the induction point and the next induction point in the direction of travel of the sorter carts is considered one virtual sorter since within that segment the tray sorting machine performs all sorting functions along its length. A virtual sorter as the term is used herein has the foregoing meaning and may make use of any type of closed loop parcel sorting machine such as a cross-belt or tilt-tray sorter, or the equivalent.
Sorting systems such as cross-belt or tilt-tray sorters are often used to unload items to outlet chutes (also called collection chutes) from which items are manually taken and placed in containers or carts for subsequent processing. This operation is limited by the amount of space available around the periphery of the sorting machine's oval track. In one common version of this process, packages and flats are loaded into tubs on adjoining racks or into mail sacks mounted on carts. The carts are lined up in a formation surrounding the sorter. The human worker stands in an five to six foot wide aisle between the sorter track's outlet chutes and the carts or racks, which may be positioned both below the outlet chutes and on the other side of the aisle. The foregoing arrangement makes poor use of the available space. The present invention seeks to provide an improved cart for use with a closed loop parcel sorting machine permitting more efficient manual handling of sorted items.
A number of designs for mail carts and sorting racks are known, including those shown in U.S. Pat. No. 6,715,614 FIGS. 28 and 29. Bags can be described as having length, width and depth dimensions. The plastic bags shown in the '284 publication are oriented edgewise, such that the frontwardly opening mouths of the bags are oriented so that the widthwise dimension of the bag is oriented substantially vertically, presenting an opening that is long vertically and narrow horizontally. Mail carts according this publication use horizontally oriented shelves (FIG. 15) or shelves pitched from side to side (FIG. 19). The present invention takes a different approach to mail cart structure.